The ink used in ink-jet printers comprises typically 20% by volume of pigment or dye with traces of various additives, some of which are volatile. The balance, i.e. substantially 80%, is water. When a swath of such ink is deposited on a print media it requires a drying time before the next swath is printed to avoid bleeding problems between the swaths. An end of plot drying time is also required to avoid ink becoming smeared during transfer of the print media to the next stage.
To allow the ink to dry naturally takes a relative long time, which has an adverse effect on throughput, so inkjet printers and other hardcopy apparatus which are in heavy use are provided with active drying systems, which eliminate moisture content from the printed surface as quickly as possible. Typically the active drying system comprises a fan and ducting system to blow air over the ink in the print zone, and/or a heater arranged under the printing platen to evaporate the moisture.
Since the vapour created by the drying system is predominantly water, the atmosphere in a room containing a hardcopy apparatus in heavy use can become unacceptably humid, with condensation forming on windows and walls. A large ink-jet printer can produce approximately 1 litre of water per hour.
Accordingly, various methods have been proposed to prevent discharge of the water vapour to the environment. In one method, the vapour emerging from the printzone is condensed and conveyed outside of the hardcopy apparatus, for example to a nearby drain. This has the disadvantage of requiring an external hose connection and requires the apparatus to be located close to a local drain. Moreover, since the condensate will contain chemicals in the form of volatile constituents and unused ink, there may be environmental considerations which do not allow the condensate to be discharged in this way.
In another method, the condensate is collected in a dedicated container within the hardcopy apparatus. This has the disadvantage of requiring within the apparatus additional space which needs to be readily accessible. In addition, time and effort are required to empty the container. The container also requires maintenance. Problems can also arise if the user or service engineer forgets to empty the container before it is full.